Electrostimulation systems are designed to treat neurological disorders and for management of chronic pain. A typical electrostimulation system involves the use of a generator and a stimulation lead having a plurality of electrodes. The generator is coupled to the stimulation lead in order for the electrodes to provide low level electrical impulses that the stimulation lead applies to the treatment area. For example, the stimulation lead may be implanted in the epidural area of the body, where the electrical impulses stimulate targeted nerves. The stimulation may result in the brain replacing the sensation of pain with a more pleasing sensation called paresthesia.
For deep brain stimulation (DBS), the stimulation leads used for spinal cord stimulation (SCS) may not be adequately sized. A smaller stimulation lead, and correspondingly smaller electrodes, may be desired. However, providing such a smaller stimulation lead has posed some challenges in that merely resizing lead technology used for SCS has proven ineffective to provide a smaller stimulation lead, such as one useful for DBS, having desirable functional and aesthetic attributes. For example, according to one technique for providing a stimulation lead for use in SCS, a mold is used to manufacture the stimulation lead where the electrodes are placed in the mold, wires are soldered, or otherwise attached to the electrodes, and a fill material is injected into the mold. Injecting the material has posed some challenges because the volume of the lead is reduced and therefore air, vapor, or other gaseous material may become more easily trapped.
One technique for reducing or eliminating the trapped gaseous material involves injecting the fill material at higher pressure. The high pressure may result in the gas being pushed out of the mold before the fill material cures. This technique, however, may result in the weakening and/or detachment of wire contacts coupled to the electrode. Another technique may involve heating the fill material to decrease its viscosity in order to more easily fill the areas where gas may be trapped. This technique, however, may result in the discoloration of the material due to the increased temperatures, which is aesthetically unappealing. Additionally, heating the fill material may result in a change of the chemical properties of the resulting lead, which is unacceptable considering the need for bio-compatibility of the stimulation lead and the human body. Consequently, a need exists in the art for other techniques for removing gases.